This invention relates to rotary fluid displacement apparatus, and in particular, to fluid compressor units of the scroll type.
Scroll-type apparatus are well known in the prior art.
For example, U.S. Pat. No. 801,182, discloses a device including two scroll members each having an end plate and a spiroidal or involute spiral element. The scroll members are maintained angularly and radially offset so that both spiral elements interfit at a plurality of line contacts between their spiral curved surfaces, to thereby seal off and define at least one pair of fluid pockets. The relative orbital motion of these scroll members shifts the line contact along the spiral curved surfaces and, therefore, changes the volume in the fluid pockets. The volume of the fluid pockets increases or decreases dependent on the direction of orbital motion. Therefore, a scroll type apparatus is applicable to compress, expand or pump fluids.
Sealing along the line contact must be maintained because the fluid pockets are restricted or defined by the line contact between the two spiral elements and, as line contact shifts along the surface of spiral elements, the fluid pocket changes volume by the relative orbital motion of the scroll members. In some prior art devices, both scroll members are supported on a crank pin or shaft which is disposed at end portions of drive shafts to accomplish the relative orbital motion between the scroll members. The scroll members are thereby supported in a cantilever manner. Therefore, a slant may arise between the drive shafts and the cantilever supported scroll members, whereby axial line contact between the spiral elements is not maintained. In other prior art devices, one of the scroll members is fixedly disposed in a housing and the axial slant of the scroll member is thereby prevented. However, the other scroll member must be supported on the crank pin of the drive shaft, therefore, axial slant of this scroll member by the cantilever support is not resolved. In addition, the movement of the orbiting scroll member is not rotary motion around the center of the scroll member, but is orbiting motion caused by the eccentrical movement of the crank pin moved by the rotation of the drive shaft, therefore axial slant easily arises. When the axial slant occurs several problems arise; primarily sealing of the line contact, vibration of the apparatus during operation and noise caused by striking of the spiral elements.